first check the coolant level,sometimes when it is low not enough coolant makes it into the heater core to warm the cabin.If that isn't the case flush the heater core. just unhook the hoses and take a water hose and start with the upper hose then lower hose and back and forth till all crap if any comes out. if that isn't it well then move on to the more difficult stuff like the blend door and the actuator.

out of all the jeeps in this town the d**n gremlin had to invade mine

I've done so much,with so little for so long i can practicly do anything with nothing